My home PBX was installed and working well. However, today I discovered that my VoIP provider started blocking outgoing calls from the Asterisk user agent. The fix is to edit /etc/asterisk/sip.conf and change the useragent line. However, the distro I chose was very much a PBX appliance. No SSH, no shell, only Web UI access. But, I knew it was a Linux box, probably CentOS or RHEL based. So i decided I’d try my hand at retaking control of the system.

First step was to boot into single-user mode. This was quite easy. Just interrupt GRUB and add “single” to the kernel options.

Once at the shell prompt, you might want to add a regular user.

adduser matt

Then, try changing the root password.

passwd root

Unfortunately this does not work. It fails with “Authentication Token Manipulation Error”. To fix this, use pwconv. (Thanks to mohammedz)

Then try passwd root again, it should work this time.

Next, enable ssh. Run chkconfig sshd on.

Now, edit /etc/asterisk/sip.conf and change the useragent. 🙂